In recent years, solid solutions have shown promising results as functional materials for different applications. These materials have tunable physiochemical properties and electronic properties, and are being intensively studied for next generation electrochemical charge storage as
well as noble metal free low cost electrocatalyts. In the present work, Magnesium Nickel Oxide (MgNiO2) solid solution is prepared by molten salt synthesis. MgNiO2 particles having octahedron shaped morphology with size of 550 nm with an agglomerative behavior was observed
through morphological studies. Raman studies revealed presence of three two-phonon modes as well as two one-phonon modes, which confirm the phase purity of MgNiO2 sample. MgNiO2 particles behaved as a promising supercapacitor candidate by exhibiting a large specific capacitance
of 76 F/g. It also revealed electrochemical stability over an expansive potential range under the presence of 0.5 mol L-1Sodium Sulfate (Na2SO4) electrolyte, having a high energy density of nearly 51 Wh/kg with a power density of nearly 825 w/kg. Further, MgNiO2
particle showed improved electrocatalytic potential towards Hydrogen Evolution Reaction (HER) in 1 mol L-1 Potassium Hydroxide (KOH) alkaline medium, by demonstrating an overpotential of 0.636 V with a Tafel slope of 0.22205 v/dec. Based on these observed promising results, it can
be conclusively inferred that MgNiO2 solid solution is a potential candidate for environmental friendly high voltage supercapacitor and HER electrocatalyst applications.
